/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util;

import java.util.concurrent.atomic.AtomicLong;

/**
 * Base implementation of {@link Constant}.
 */
public abstract class AbstractConstant<T extends AbstractConstant<T>> implements Constant<T> {

  private static final AtomicLong uniqueIdGenerator = new AtomicLong();
  private final int id;
  private final String name;
  private final long uniquifier;

  /**
   * Creates a new instance.
   */
  protected AbstractConstant(int id, String name) {
    this.id = id;
    this.name = name;
    this.uniquifier = uniqueIdGenerator.getAndIncrement();
  }

  @Override
  public final String name() {
    return name;
  }

  @Override
  public final int id() {
    return id;
  }

  @Override
  public final String toString() {
    return name();
  }

  @Override
  public final int hashCode() {
    return super.hashCode();
  }

  @Override
  public final boolean equals(Object obj) {
    return super.equals(obj);
  }

  @Override
  public final int compareTo(T o) {
    if (this == o) {
      return 0;
    }

    @SuppressWarnings("UnnecessaryLocalVariable")
    AbstractConstant<T> other = o;
    int returnCode;

    returnCode = hashCode() - other.hashCode();
    if (returnCode != 0) {
      return returnCode;
    }

    if (uniquifier < other.uniquifier) {
      return -1;
    }
    if (uniquifier > other.uniquifier) {
      return 1;
    }

    throw new Error("failed to compare two different constants");
  }

}
